Number of base 5 circular n-digit numbers with adjacent digits differing by 1 or less.

Terms

a(0) =1a(1) =5a(2) =13a(3) =29a(4) =73a(5) =185a(6) =481a(7) =1265a(8) =3361a(9) =8993a(10) =24193a(11) =65345a(12) =177025a(13) =480641a(14) =1307137a(15) =3559169a(16) =9699841a(17) =26452481a(18) =72173569a(19) =196989953a(20) =537802753a(21) =1468536833a(22) =4010582017a(23) =10954043393a(24) =29920862209a(25) =81733033985a(26) =223274237953